Monday, July 2, 2012

Somatic or Genetic Effects?

A somatic effect is roughly defined as a visible change in bodily characteristics or processes. A tumor would be indicative of a somatic change, as would be changes in white blood cell counts.

A genetic effect is defined by a mutation in DNA or a mutation in the progeny of an irradiated cell.

The concept of "permissible dose" was and continues to be based on somatic changes, not genetic ones.

Some background:

Studies on chromosomal changes conducted as early as 1928
found genetic changes in the absence of somatic alterations. However, scientists
disagreed upon the significance of those findings for somatic, or bodily changes, for decades.

In 1925 a “tolerance dose” for
radium was proposed as a guide for workplace exposure although the author of
the proposed dose argued there was no safe level of exposure (Calabrese). In
1928 a national committee, the U.S. Advisory Committee on X-Ray and Radium
Protection (NCRPM) made up of physicians and scientists formed and offered
suggestive guidelines for safe handling of radiation; however, this committee
had no official standing or statutory authority (Walker, 7). An International Committee
on Radiation Protection, the ICRP, was also established in 1928, issuing its
first publication that year on radiation safety.The
ICRP recommended a tolerance dose for workers based on 1/100 of the dose of radium
believed to be needed to produce visible reddening of the skin. The
US NCRPM did not issue recommendations for tolerance doses for radium in their
radiation exposure standards until 1934; once proposed the standards were
significantly higher (ten times) than those proposed in 1925. The
new standards presumed that an equilibrium state existed between somatic injury
and repair.Proposed,
but not enforceable, new guidelines by these committees did not halt the
continued use of radium in homeopathic medicine.

In 1947 the NCRPM, acting in response to AEC
pressure, introduced the idea of maximum “permissible dose” for occupational
exposure; although, the author of this concept, G. Failla of Columbia University,
recognized that if genetic hazards served as the basis for setting the
tolerance dose, than only zero exposure could serve. Fallia therefore rejected
genetic hazards as the basis for setting the permissible dose, favoring instead
a formulation that emphasized somatic (i.e., bodily), non-genetic detection (Calabrese).
There was considerable push back to Fallia’s formulation of permissible dose
from geneticists on the committee concerned about the long term effect of exposure
on human chromosomes, especially across generations. However, proving genetic changes
in human genes before explication of DNA in 1953 was challenging. Permissible
dose therefore was understood as accepting some level of genetic injury (Calabrese).

Recent
laboratory research studies on the effects of radiation explain how genetic changes produce somatic changes across time. The “bystander effect” and “delayed effect” describe
the phenomena whereby cells not directly targeted by the radiation can exhibit
damage and produce damaged progeny over time. Furthermore, the research on
alpha particles demonstrates conclusively that transversal of a single alpha
particle can break DNA bonds. Thus, todays sophisticated technologies for
viewing DNA alterations are better able to link DNA mutations to subsequent
somatic changes, such as tumor development.

About Me

I am a Professor at a large public university. I study political economy and biopolitics (the politics of life). My interests are diverse but are broadly concerned with economic, social and environmental justice. I have published 5 books: Crisis Communication, Liberal Democracy and Ecological Sustainability: The Threat of Financial and Energy Complexes in the Twenty-First Century (2016); Fukusima and the Privatization of Risk (2013); Constructing Autism (2005); Governmentality, Biopower and Everyday Life (2008/2011); Governing Childhood (2010).
I also participated in an edited collection on Fukushima: Fukushima: Dispossession or Denuclearization (2014).